Controlled molten metal deposition

Abstract

An additive manufacturing system includes an apparatus to facilitate production at the microscale using metal sheet as feedstock. The additive manufacturing system uses energy from a pulsed laser beam for ejection of metallic droplets to consolidate a part in a layer-by-layer manner. The system may include an enclosure, a stage, a substrate, a feedstock advancement device, an optically transparent support, and a controller.

What is claimed: 
     
       1. An additive manufacturing system, comprising:
 an enclosure, the enclosure defining an inlet, an exhaust, and an aperture and comprising a substrate upon which a workpiece is to be formed and an optically transparent support disposed between the aperture and the substrate; 
 a pulsed laser, disposed outside the enclosure, positioned to emit one or more pulses through the aperture and into the enclosure; 
 a feedstock comprising a sheet or ribbon of material that is moveable with respect to the transparent support; 
 a feedstock advancement device, at least partially disposed within the enclosure, to advance the feedstock within the enclosure and to maintain the feedstock adjacent the optically transparent support; and 
 a controller to cause the pulsed laser to emit one or more pulses through the aperture and the optically transparent support to impinge upon a selected portion of the feedstock to liquefy the selected portion of the feedstock and discharge a droplet of the material from the feedstock onto the substrate or onto a workpiece on the substrate. 
 
     
     
       2. The additive manufacturing system of  claim 1 , wherein the pulsed laser is controllable, via the controller, in an X-plane, a Y-plane and/or both the X-Y planes to raster the laser across the feedstock. 
     
     
       3. The additive manufacturing system of  claim 2 , further comprising at least one scanning mirror and wherein the pulsed laser is controllable, via the controller and at least one scanning mirror, in an X-plane, a Y-plane and/or both the X-Y planes to raster the laser across the feedstock. 
     
     
       4. The additive manufacturing system of  claim 1 , wherein the inlet is connected to a gas supply line delivering an inert gas, and wherein the exhaust is connected to an external environment to exhaust gas or fumes from the enclosure. 
     
     
       5. The additive manufacturing system of  claim 1 , wherein the sheet or ribbon of material comprises a metal, a metal alloy, a plastic, a polymer, a ceramic, a semiconducting material, or a composite of two or more materials. 
     
     
       6. The additive manufacturing system of  claim 1 , wherein the pulsed laser comprises a nanosecond (ns)-pulsed laser, a femtosecond (fs)-pulsed laser, or a picosecond (ps)-pulsed laser. 
     
     
       7. The additive manufacturing system of  claim 1 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses having a duration that ranges from about 1 ns to about 500 ns. 
     
     
       8. The additive manufacturing system of  claim 7 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses having a duration of at most 200 ns. 
     
     
       9. The additive manufacturing system of  claim 8 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses having a duration of about 30 ns. 
     
     
       10. The additive manufacturing system of  claim 1 , wherein the pulsed laser has a power density or laser fluence between about 0.001 and about 100 J/cm2. 
     
     
       11. The additive manufacturing system of  claim 1 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses that impinge upon the feedstock with a power density or laser fluence that ranges from about 0.001 J/cm2 to about 100 J/cm2. 
     
     
       12. The additive manufacturing system of  claim 11 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses that impinge upon the feedstock with a power density or laser fluence that ranges from about 1.0 J/cm2 to about 30 J/cm2. 
     
     
       13. The additive manufacturing system of  claim 12 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses that impinge upon the feedstock with a power density or laser fluence that ranges from about 1.4 J/cm2 to about 2.8 J/cm2. 
     
     
       14. The additive manufacturing system of  claim 1 , wherein the controller is configured to cause the pulsed laser to heat a portion of the feedstock to a temperature that ranges from about 0.4 T m  to about 0.7 T m  for the feedstock material. 
     
     
       15. The additive manufacturing system of  claim 14 , wherein the controller is configured to cause the pulsed laser to heat a portion of the feedstock to a temperature of about 0.6 T m  for the feedstock material. 
     
     
       16. The additive manufacturing system of  claim 1 , wherein the controller is configured to adjust a print resolution of the workpiece on-the-fly between a first activation of the pulsed laser to emit one or more pulses onto a first selected portion of the feedstock and a second activation of the pulsed laser to emit one or more pulses onto a second selected portion of the feedstock. 
     
     
       17. The additive manufacturing system of  claim 1 , wherein the controller is configured to control the pulsed laser to adjust a print resolution of the workpiece on-the-fly by changing at least one of a pulse shape, a pulse duration, a pulse frequency, a pulse power density or laser fluence, a pulse beam size or pulse width, or a number of pulses between the first activation and the second activation. 
     
     
       18. The additive manufacturing system of  claim 1 , wherein the controller is configured to control a spot size of the one or more pulses by offsetting a focal plane of the pulsed laser relative to an upper surface of the feedstock. 
     
     
       19. The additive manufacturing system of  claim 1 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses that impinge upon the feedstock with a laser beam spot size that ranges from about 1 μm to about 1000 μm. 
     
     
       20. The additive manufacturing system of  claim 19 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses that impinge upon the feedstock with a laser beam spot size that ranges from about 10 μm to about 30 μm. 
     
     
       21. The additive manufacturing system of  claim 20 , wherein the controller is configured to cause the pulsed laser to emit one or more pulses that impinge upon the feedstock with a laser beam spot size of about 20 μm. 
     
     
       22. The additive manufacturing system of  claim 1 , wherein the droplet discharged from the feedstock is deposited onto the substrate or onto the workpiece on the substrate directly underneath the selected portion of the feedstock. 
     
     
       23. The additive manufacturing system of  claim 1 , wherein the substrate is movable. 
     
     
       24. The additive manufacturing system of  claim 1 , further comprising a moveable stage disposed within the enclosure, and wherein the substrate is positioned on the moveable stage. 
     
     
       25. The additive manufacturing system of  claim 1 , wherein the feedstock advancement device comprises one or more guide rollers. 
     
     
       26. The additive manufacturing system of  claim 1 , wherein the feedstock advancement device comprises a first set of guide rollers on a first side of the optically transparent support and a second set of guide rollers on a second side of the optically transparent support. 
     
     
       27. The additive manufacturing system of  claim 1 , wherein the controller is configured to advance the feedstock, via the feedstock advancement device, following the discharge of the droplet of the material from the feedstock. 
     
     
       28. The additive manufacturing system of  claim 1 , wherein the controller is configured to cause the pulsed laser to emit a plurality of pulses through the aperture and the optically transparent support to impinge upon a corresponding plurality of selected portions of the feedstock to liquefy the selected portions of the feedstock and discharge a corresponding plurality of droplets of the material from corresponding portions of the feedstock, each of the plurality of droplets being deposited onto the substrate or onto a workpiece on the substrate underneath the respective selected portions of the feedstock. 
     
     
       29. The additive manufacturing system of  claim 1 , wherein the controller is configured to advance the feedstock, via the feedstock advancement device, following the discharge of a plurality of droplets of the material from the feedstock from a plurality of selected portions of the feedstock. 
     
     
       30. The additive manufacturing system of  claim 1 , wherein droplet of the material is discharged from a bottom portion of the feedstock. 
     
     
       31. The additive manufacturing system of  claim 1 , wherein the thickness of the feedstock ranges from about 0.5 μm to about 100 μm. 
     
     
       32. The additive manufacturing system of  claim 31 , wherein the thickness of the feedstock ranges from about 4 μm to about 8 μm. 
     
     
       33. The additive manufacturing system of  claim 1 , wherein the distance between the feedstock to the substrate ranges from about 100 μm to about 1 m. 
     
     
       34. The additive manufacturing system of  claim 1 , further including means for applying an electric field to the droplet as it travels from the feedstock to the substrate. 
     
     
       35. The additive manufacturing system of  claim 1 , further including means for applying a magnetic field to the droplet as it travels from the feedstock to the substrate. 
     
     
       36. The additive manufacturing system of  claim 1 , wherein the location of the transparent support is fixed within the enclosure.